<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>设置函数参数的默认值</title>
</head>
<body>
    <script>
        // ES5 方式
        function fn(name,age) {
            name = name || "tom";
            age = age || 17;
            console.log(name + "," + age);
        }
        // ES5 + 类型检查
        function fn2(name,age) {
            name = (typeof name !='undefined' ? name : 'tom');
            name = (typeof age !='undefined' ? age : 17);
            console.log(name + "," + age);
        }
        // ES6 方式
        function fn3(name='tom',age=17) {
            console.log(name + "," + age);
        }

        fn();
        fn2();
        fn3();
    </script>
</body>
</html>